Preheat oven to 355°F. Line baking sheet with parchment paper. Spray with baking spray and lightly dust with flour. Set aside
Separate egg whites from egg yolks. Beat egg whites on high speed for 2. Continue beating and slowly add sugar. Beat another 2 minutes, until stiff peaks form.
In a separate bowl, beat egg yolks and sour cream. Add yolk mixture to egg whites and mix on low speed to combine.
In a small bowl, combine flour and baking powder. Add the flour to the batter. Mix on low speed for a few seconds. Turn of the mixer. With a spatula continue folding the batter until well incorporated.
Pour batter into the baking sheet. Bake 12-14 minutes.
Once baked, let cool about a minute. With a sharp knife, release edges of cake from baking sheet.
Roll cake into a roulade. Set aside to completely cool.